Apparatus for use by skiers on which they may simulate the motions, exertions and techniques required in skiing has been built and sold for several years. In particular U.S. Pat. No. 3,524,641 was issued to Robert J. Ossenkop on Aug. 18, 1970, for a device comprising a movable carriage on a set of rails. The carriage of that device is constrained in its movement on the rails by flexible members attached to both the carriage and to transverse members between the rails near each end of the set of rails, and a user can move the carriage from side to side on the rails to simulate the Wedeln or "parallel" technique of skiing.
U.S. Pat. No. 3,547,434 was issued to the same inventor on Dec. 15, 1970. This later referenced patent is for a device similar to the first device, but comprising a number of improvements, such as movable footrests on the carriage whereby a user may simulate turning and edging techniques in addition to parallel sking; and, in some embodiments may also move the feet relative to one another.
The inventions referenced above each include a safety strap attached to a transverse member between the parallel rails and to the carriage on the rails in addition to the flexible member by which the carriage is constrained to travel on the rails. The purpose of the safety strap is to provide for the situation in which the aforementioned flexible member might rupture on one side of the carriage, providing a sudden force urging the carriage to the side where the flexible member remains unruptured, which sudden force could dislodge a user and perhaps cause serious injury. The safety strap in such instance provides a restoring force toward the center tending to lessen the amplitude of carriage displacement that might otherwise occur.
In the copending parent application, Ser. No. 080,755, an (exerciser) is disclosed having a pair of spaced apart rails, a platform for riding on the the rails, a first resilient element providing a first restoring force on the platform, and a second resilient element providing a second restoring force on the platform. The second resilient element has an adjustment element contacting the second resilient element in at least three points.
In the latter (exerciser) the rails are held in a spaced apart relationship by a brace element in the center, which is fastened to the rails by screw-type fasteners, and by transverse elements fastened at the ends of the rails. The transverse elements at the ends are tubular in form, and the rails pass through openings in the tubular transverse elements, fastening to a bracket internal to each tubular transverse element. This joining arrangement is illustrated by FIG. 1A and FIG. 1B. Rails 301 and 303 pass through holes 305 and 307 respectively into tubular transverse element 309. Inside, the rails are fastened to a bracket 311 by screw fasteners 313 and 315. Rubber-like end caps 317 and 319 close the ends of the tubular transverse element after assembly and act as non-skid pads in contact with the floor in operation. In the copending application, the end caps are of molded rubber-like material, and disk-like pieces carrying designs and lettering are added for identification and esthetic effect. This particular method of joining and spacing the rails has not proved entirely satisfactory in terms of cost and ease of assembly, and in terms of strenght and rigidity of assembly, and the multiple-piece construction of the end caps has also provided to be relatively expensive.
Also in the (exerciser) disclosed in the copending parent application, the first resilient element is fastened to the carriage that rides on the rails, and also is fastened to the tubular transverse elements at each end. The first resilient element is fastened to the carriage by a clamp, and at each end, the resilient element, that in the preferred embodiment has the form of a strap of rubber-like material, passes over, around, and back under the tubular transverse element, terminating at a clamp that is bolted through the tubular transverse element. FIG. 2A and 2B show the arrangement of the bracket and clamp, and the fastening of the first resilient element in the aforementioned application.
As shown by FIGS. 2A and 2B, first resilient element 321 passes over, around, and back under tubular transverse element 309, and then passes between two clamping elements 323 and 325. Bolts 327 and 329 pass through transverse element 309 and also through each of clamping elements 323 and 325. Clamp knobs 331 and 333 engage bolts 327 and 329 and provide pressure to secure the resilient element by friction. This fastening arrangement for the first resilient element at the ends of the exerciser has proven to present a difficulty in that as the carriage moves from one side to the other, urged by a user, stretching the first resilient element, friction over the area of contact where the first resilient element passes over, around and under each of the tubular transverse elements causes wearing effects on the resilient element, resulting in premature failure. Another difficulty is in the length of the portion of the resilient element that stretches when the carriage moves to the side of the exerciser away from the clamp at the end transverse member. In the aforementioned device of the prior art, moving the carriage to one end stretches the resilient element on the opposite side by more than 65 percent.
FIG. 3 is a side view of a pivot platform 335, foot platforms 337 and 339, and associated elements from the aforementioned copending application. Foot pad 337 is pivoted at point 341, and foot pad 339 is pivoted at point 343. The two foot pads are joined by a link 345 so that as they pivot in operation they are constrained to pivot together. The pivot point for each foot pad is substantially at the center, so D1=D2.
The position of the pivot point for each foot pad relative to the width of the foot pad has proven to be very important in operation to simulate parallel skiing technique. In FIG. 3, the letter L near one foot pad indicates the pad where a user would place his or her left foot. The right foot would then be on the other foot pad labeled R. When simulating a right turn on such an apparatus, the weight is shifted to the left foot, and the foot pads must rotate clockwise relative to the plane of FIG. 3. With the weight on the left foot pad, with the pivot in the center of the pad as shown, the force to rotate the foot pads is just as likely to be counter-clockwise as it is to be clockwise around the pivot. Exactly the opposite is true when simulating a left turn, with the same uncertain result with the right foot and the right foot pad. A way to ensure that the foot pads rotate in the proper direction is needed.
FIG. 4 is a partial section through foot pad 339, pivot platform 335 and a carriage 337 that rides on the rails 301 and 303. A pivot shaft 347 passes through flanges of both the pivot platform and the foot pad and the foot pad rotates about the pivot shaft. The pivot shaft passes through bushings such as bushing 349. The shaft is retained by clip retainers such as retainer 351. The pivot platform is mounted to the carriage by screw fasteners. The assembly has a considerable number of parts to be manufactured and assembled, and has proven to be relatively expensive to produce.
Also shown in FIG. 4 is a clamp bar 353 used with two bolts 359 and 361 and two clamp knobs 355 and 357 to clamp resilient element 321 under the carriage. This clamp arrangement is typical of clamps used with the apparatus of the aforementioned copending parent application. The round clamp bar presses on the resilient element in a relatively narrow region and has been shown to cause wear on the resilient element and to also exhibit some problems in strength and rigidity.
Also shown by FIG. 4 is a roller 363 pivoting on a bolt 365 secured by a nut 367. A second resilient element 369 passes over this roller. The roller assembly is typical of several such rollers used in the apparatus. A problem has developed in assembly and operation in that the flanges through which bolt 365 passes and between which roller 363 operates may be drawn in excessively in assembly by excessive tightening of nut 367, restricting the ability of roller 363 to freely rotate and hindering operation of the apparatus. An assembly is needed which is tolerant of assembly pressure.